Java从KeyPair对象检索公共密钥的实际值

Question

我想问一下如何从KeyPair对象中检索私钥和公钥的实际值，因为我需要将它们导出并保存在数据库中。

KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
kpg.initialize(1024);
KeyPair keyPair = kpg.genKeyPair();

System.out.println("Public key " + keyPair.getPublic());
System.out.println("Private key " + keyPair.getPrivate());

输出为：

Public key Sun RSA public key, 1024 bits
  modulus: 105712092415375085805423498639048173422142354311030811647243014925610093650322108853068042919471115278002432342007597147610508132502035047888382465733153739247741208519707861808073276783311634229563965825609200080862631487160732889423591650215084096832366499080850540875321197564283324922935557797293830551071
  public exponent: 65537
Private key sun.security.rsa.RSAPrivateCrtKeyImpl@35e71

Answer 1

它可能是最容易使用的keypair.getPublic.getEncoded()或keypair.getPrivate.getEncoded()：

RSA私钥以PKCS＃8格式编码，而公钥以X.509格式编码。

KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
kpg.initialize(2048);
KeyPair keyPair = kpg.generateKeyPair();
PublicKey pub = keyPair.getPublic();
PrivateKey prv = keyPair.getPrivate();

byte[] pubBytes = pub.getEncoded();
byte[] prvBytes = prv.getEncoded();

// now save pubBytes or prvBytes

// to recover the key
KeyFactory kf = KeyFactory.getInstance("RSA");
PrivateKey prv_recovered = kf.generatePrivate(new PKCS8EncodedKeySpec(prvBytes));
PublicKey pub_recovered = kf.generatePublic(new X509EncodedKeySpec(pubBytes));

System.out.println("Private Key: \n" + prv_recovered.toString());
System.out.println("Public Key: \n" + pub_recovered.toString());